Electron discharge device



Oct. 15,1946. 5. w. HEROLD 2,4@9,485

" ELECTRON DISCHARGE DEVICE i-"ned Jan. 24, 1945 2 Sheets-Sheet 1 INVENTOR.

HERWD D L Q R s H w E 2,409,485 ELECTRON mscmmus DEVICE I Filad Jan. 24, 1945 zsheets-shaat 2 INVENTOR. +300 DWARD W. HEROLD- @www ATTORNEY Patented Got. E5, 3946 er I: B.

2,d09,d85 EEECTRON DISCHARGE DEVICE Edward W.',Eerold, Kingston, N. 3., asslgnor to Radio Qorporation of America, a corporation of Delaware 1 Application January 24, 1945, Serial No. 574,263

The invention covered herein may be manufactured and used by or for the Government of the United States for' any governmental purpose without payment tome or assigns of any royalty thereon.

My invention relates to electron discharge devices, more particularly to such devices suitable for use at ultra high frequencies and utilizing a beam of electrons which is periodically deflected for varying the output of the device.

Electron discharge devices to which the present invention is directed are used as mixers and amplifiers, particularly at high frequencies where the advantages of low input conductance and capacity are important.

One form of beam deflection tube includes a cathode and associated elements for providing a directed beam of electrons of rectangular cross section, which beam is directed toward a collector through a, beam focusing and beam deflection system, the electron beam being deflected across an apertured element to determine the amount of current to the collector. The aperture may be bisected by a rod-like element, thus producing in effect a double aperture. Positioned between the collector and apertured element may be a suppressor which is aligned with the aperture in the apertured element.

In the copending application of Charles W.

Mueller, Serial No. 451,339 filed November 1, 1944, and assigned to the same assignee as the present application, there is shown and described a beam deflection tube of the general ty e described above. This tube utilizes a flat plate type of construction for insuring accurate alignment of v 7 Glalma. (171. 315- 17) normal standards some require adjustment by means of correcting magnets. Although some of the trouble was probably due to surface potential variations on various parts of the electrode if these plates were operated at the same potential as surrounding electrodes, since then no tending transversely of the beam path. They are oppositely disposed from each other to provide a pair of successively positioned apertures. To maintain these plates in spaced relationship and to define the rectangular apertures, separating members, extending parallel to th beam path and providing supporting arms, are positioned at the top and bottom of the plates. These longitudinally extending arms also support oppositely disposed deflecting electrodes between which the beam is directed and by which the beam is deflected.

While many tubes of this type perform up to electric fields would be present to distort the beam in case of misaligned parts. However, in this event focusing of the beam, which is essential in a tube whichlis to have high sensitivity, must be done in some other way.

In the present type of beam deflection tube the centering of the beam is accomplished by a differential bias applied'to the deflecting electrodes. This requires troublesome blocking condensers and D.-C. separation of the deflection plates. The deflecting electrodes are also relied upon in combination with the apertured elements to provide a focusing action on the electron beam, thus necessitating the use of the deflection plates for two functions with the attendant mechanical and electrical dimculties.

It is, therefore, a. principal object of my invention to provide an electron discharge device of the beam deflection type of improved design in which normal performance can be substantially assured.

Another object of my invention is to provide such a device in which the disadvantages ofmisalignment of deflection plates are eliminated or reduced to a minimum.

Another object of my invention is to provide an electron discharge device of the beam deflection type having an electrode system in which no bias is needed on the deflection plates so as to eliminate the troublesome blocking condenser and D.-C. separation of the deflection plates.

A further object of my invention is to provide an electron assembly in which the focusing anddeflection portions can be separated whereby tubes can be built which will have better electron beam alignment on the average than previously obtained.

The novel features which I believe to be char acteristic of myinvention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawings in which Figure 1 is an elevation of an electron discharge device made according to my invention with parts removed to show details of construction, Figure 2 is a transverse section taken along the line 2-2 of Figure 1, Figure 3 is a transverse section taken along the line 3-3 of Figure 1, Figure 4 is an exploded perspective showing the arrangement of the parts 'of a mount assembly of the electron discharge device shown in Figures 1 to 3 inclusive, Figures 5, 6 and 7 show details of construction of the focusing portion of the assembly made according to my invention, and Figure 8 is a schematic diagram showing the lens effect produced by the arrangement shown in Figures 5, 6 and 7.

As shown in Figures 1 to 3 inclusive, the evacuated metal envelope in of oval shape is provided with a metallic header 1 i through which the various leads and supports for the electrodes extend, these leads being insulatingly sealed through the header member. The envelope and header may be made of non-magnetic material such as stainless steel.

Mounted within the envelope is a cathode electrode assembly comprising the indirectly heated cathode i2 provided with the cathode and heater-leads l3 and I4. The cathode is surrounded by means of the shielding member i having a front cover member 16 provided with an elongated aperture l6 through which the electrons from the cathode l2 are directed. This electrode assembly is mounted between. a pair of insulating spacer members I! and I8 and clamped to the same by means of the strap i9 and positioned between the spacer members which may be mica by means of the ears such as 20-40 on member it. Mounted at the other end of the envelope is a collector 2| in the form of a loop supported by means of the support and lead 22.

Positioned between the cathode and the collector is the aperture, lens and beam. deflecting electrode assembly. The aperture, lens and beam deflecting electrode assembly is formed as a unit and includes the aperture and lens portion, designated generally at 25 and which will be described in' greaterdetail below, provided with horizontally extending arms 26' and 21 -which support the deflecting electrodes 28, 29

and the intercepting wire 30 anchored at its lower end and maintained in tension by means of the spring anchor 3| permitting expansion and contraction of the wire but always assuring alignment. The wire is positioned in and guided by the slots 26' and 21' at the ends of the arms 26 and 21. Mounted at the collector end of the assembly is a pair of shields 32 and 33 which are supported by the header'and are secured to the arms 26 and 21. port the apertured suppressor electrode 34 having These shields in turn supthe apertur 34' by means of the glass bead assemblies such as 35 and 35'. A lead 34" is provided for the suppressor. The end of the aperture and deflecting electrode assembly adjacent the cathode I2 is provided with a pair oftransverse shield members 40 and M. These shield members provide a linear accelerating field for the electron beam and prevent stray electrons aperture l6 through the aperture assembly 25 between the deflecting electrodes 28 and 29 and are deflected across the intercepting wire 30 passing through the aperture 34 of suppressor 34 .to the collector M.

A getter wire or trough 31 is mounted at the top of the envelope at the ends of the conductors and leads 38 and 39. A shield 36 is provided between th getter and the top of the electrode assembly.

The header is provided with a glass press 42 through which the leads 43 and 44 extend, these being in turn connected to deflecting electrodes 29 and 28. The leads 43 and 44 extend parallel to each other through the press so that a coaxial line or Lecher wire system may be conveniently connected to the same externally of the enverod-like elements 52, 53, 54 and 55. These elements may be secured to the inner surfaces of the plates by fusion welding, for example, and

the apertures are focusing electrode members 55 and 56, which are provided as best shown in Figures 2 and 3 with leads 55' and 5B for permitting the application of proper biasing voltages.

As shown in Figure 8 by applying a low or zero potential to the focusing plates 55 and 5B and a high positive potential, for example in the neighborhood of 300 volts, to'the apertured plates 50 and ii, a lens effect may be produced as indicated. The deflecting electrodes may also be maintained at a high positive potential, for example 300 volts, whereby no D.-C. potential difference exists between the apertured plates and the deflecting plates, the focusing electrodes being utilized also as centering electrodes by a biasing voltage differential ,on these two plates if this is necessary. Thus with my arrangement the electron beam starts from the cathode, is accelerated by the 300 volt aperture-plate potential and then passes through two fine collimating apertures formed by the rods on the aperture plate. Instead of entering the deflecting electrode region, the beam then passes through zero, so that the only potentials on the tube are zero and the accelerating voltage. The tube then becomes inherently a fixed focusing device independent of the applied accelerating voltage. The principle utilized here is described by H. Iams in the Proceedings of the I. R. E., volume 27, pages 103-105, February 1939.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be'employed, it will be apparent that my invention is by no 'means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departingfrom the scope of my invention as set forth in the appended claims.

What I claim as new it:

1. An electron discharge device having a cathode means for supplying a beam of electrons and an electrode in the path of said electrons, and means positioned between said cathode means and said electrode and including an electron lens system comprising oppositely disposed apertured plates adapted to have a biasing potential applied thereto and between which the beam path extends, and electrode elements mounted in registry' with said apertures on the outside of and out of contact with said plates and adapted to have a lower biasing potential applied thereto than to said plates.

2. An electron discharge device having a cathode means for supplyin a beam of electrons and an electrode in the path of said electrons, and means positioned between said cathode means and said electrode and including an electron lens system comprising oppositely disposed apertured plates adapted to have a biasing potential applied thereto and between which the beam path extends, and electrode elements mounted in reg-.

istry with said apertures on the outsideof and; out of contact with said plates and adapted to have a low biasing potential applied thereto than to said plates, and a pair of deflecting electrodes between said lens system and said electrode and between which the path of said electrons lies.

for providing an aperture between said cathode means and said focusing electrodes, said means on the facing surfaces of said plates including rod-like elements extending transversely of the beam path.

5. An electron dischargedevice having cathode'means for supplying a beam of electrons, and an electrode in the path of said electrons, an electron lens assembly positioned between said cathode means and said electrode and through which the path of the beam of electrons lies, said lens assembly including a pair of plate members having oppositely disposed -apertures therein, means for maintaining said plate members in spaced relationship, focusing electrodes mounted on the outside surfaces of said plate members and insulatingly supported thereon in registry with said apertures, a plurality of pairs of oppositely disposed rod-like elements positioned on the facing surfaces of said plate-like members and positioned between the cathode and the apertures for providing a pair of successively positioned apertures.

6. An electron discharge device having cathode means for supplying a beam of electrons, and an electrode in the path of said electrons, an electron lens assembly positioned between said cathode means and said electrode and through which the path of the beam of electrons lies, said lens assembly including a pair of plate members having oppositely disposed apertures therein, means for maintaining said plate members in spaced relationship and including a pair of elongated members extending from one side thereof, focusing electrodes mounted on the outside surfaces of said plate members and insulatingly supported thereon in registry with said apertures, and a plurality of pairs of oppositely disposed rod-like 3. An electron discharge device having cathode means for-supplying a beam of electrons and an electrode in the path of said electrons, and means positioned between said cathode means and said electrode and including an electron lens system comprising a pair of oppositely disposed plate-like members having registering apertures and spaced apart and between which the beam path lies, focusing electrodes insulatingly supported on the outside of said plates in registry with said apertures and means on the facing surfaces of said plates extending toward each other for providing an aperture between said cathode means and said focusing electrodes.

4. An electron discharge device having cathode means for supplying a beam of electrons and an electrode in the path of said electrons, and means positioned between said cathode means and said electrode and including an electron lens system comprising a pair of oppositely disposed platelike members having registering apertures and spaced apart and between which the beam path lies, focusing electrodes insulatingly supported on the outside of said plates in registry with said apertures and means on the facing surfaces of said plates extending toward each other elements positioned on the facing surfaces of said plate-like members and positioned between the cathode and the apertures for providing a pair of successively positioned apertures, and deflecting electrodes mounted on said elongated members between said focusing electrodes and the electrode in the path of said electrons.

' '7. An electron discharge device having cathode means for supplying a beam of electrons, and

an electrode in the path of said electrons, an electron lens assembly positioned betweensaid cathode means and said electrode and through which the path of the beam of electrons lies, said lens assembly including a pair of plate members having oppositely disposed apertures therein, means for maintaining said plate members in spaced relationship and including a pair of elongated members extending from one side thereof, focusing electrodes mounted on the outside surfaces of said plate members and insulating ly supported thereon in registry with said apertures and deflecting electrodes mounted on said elongated members between said focusing electrodes and the electrode in the path of said electrons.

EDWARD W. HEROLD. 

